I still have yet to unlock this... BUT I did just time this on "easy" difficulty. So the hard part is "3P Co-Op".
Get 3 people and come back.From what DE4N's guide says: "You have to do this without any of the players dying". So make sure no one dies (It's pretty easy on easy so you should be fine).
Level: Act 1 Stage 3 - "To The Queen"
Difficulty: Easy/Tadpole (You can easily dodge obstacles without using the dodge
Specific part: 3rd Area near the end (Past the 2nd checkpoint and right before the 3rd). When you have to continually jump from the middle, left or right, repeat for a small section. The specific location is in the video link below (The video is right around when you should get the achievement.)
Not counting the cutscenes you are going to hit the 5 minute/300 Second mark around this point: Link/Video:
(I recommend doing it on easy as it's A LOT slower and easier! I didn't have to use the Dodge ability once the whole time!)Note: I didn't count the "cutscenes" just incase they don't count towards the 300 seconds.